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Geomechanics and Engineering
  Volume 19, Number 5, December10 2019 , pages 447-462
DOI: https://doi.org/10.12989/gae.2019.19.5.447
 


Field instrumentation and settlement prediction of ground treated with straight-line vacuum preloading
Huayang Lei, Shuangxi Feng, Lei Wang and Yawei Jin

 
Abstract
    The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.
 
Key Words
    field instrumentation; straight-line vacuum preloading; consolidation settlement prediction; grey model
 
Address
Huayang Lei: 1.) Department of Civil Engineering, Tianjin University, Tianjin, 300072 China
2.) Key Laboratory of Coast Civil Structure Safety of Education Ministry, Tianjin University, Tianjin, 300072 China

Shuangxi Feng and Lei Wang:Department of Civil Engineering, Tianjin University, Tianjin, 300072 China

Yawei Jin: Jiangsu Xintai Geotechnical Technology Co. Ltd, Jiangsu, 214213, China
 

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